Process of making composite tubes.



UNITED STATES PATENT OFFICE.

LOUIS. r. FREDERICK, or WILKINsBImG, PENNSYLVANIA, ASSIGNOB. 'roWESTING- nousn ELECTRIC AND MANUFACTURING comPANY,'A conron rroN orPnNNsYL- Specification of Letters Patent. 4 Patented NOV. 12, 1918.

VANIA.

PROCESS OF MAKING COMPOSITE TUBES.

No Drawing.

To all whom it may concern:

a citizen of the United States, and a resident of Wilkinsburg, inthecounty of Allegheny and State of Pennsylvania, have invented a newand useful Improvement in Processes of Making Composite Tubes, of whichthe following is a specification.

My invention relates to the manufacture of composite tubes composed ofabsorbent sheet material treated with an adhesive substance, and it hasfor its object to'provide a simple and effective process for producingcomposite tubes of theabove-indicated character without the use ofelaborate apparatusor the exercise of a high degree of skill.

In the electrical insulatin art, much use is made of tubes composed 0%paper or other fibrous material coated orimpregnated with an adhesive,which may be'a varnish gum such as shellac or a synthetic resin such asthe well-known phenolic condensation products. The process heretoforecommercially employed for producing such tubes consists in treatingpaper with the adhesive material and winding the treated paper upon amandrel with the simultaneous application of heat, tension and pressure,the heat being applied for the purpose of softening the adhesive and thetension and pressure being necessary in order to unite the successivelayers into a compact mass. This procedure makes necessary the use ofrather complicated apparatus which requires the attention of highly.skilled operatives.

According to my present process, 1 proceed by wrapping upon a mandrelone or two-turns of untreated paper, and I then apply to the mandrel asuflicient number of turns of coated fibrous absorbent material to p" rea tube wall of the required thickness.-

This fibrous material, which is ordinarily pa; er, 1s provlded, beforebeing wound on the mandrel, with a dried coating of a phenolic be takenfrom the. inold without damaging the tube. Ifthc adhesive materialcontains Application filed December 18, 1914. Serial No. 871,980.

the heat has been applied for a sufiicient period to harden the adhesivematerial. When the tube and mandrel have cooled sufficiently for handlinthe mandrel may be withdrawn and any ns caused by the mold then removed.Y

The process described above produces tubes much more quickly than ispossible by the methods heretofore employed, because the hot-wrappingprocess is necessarily carried out at a slow rate. Furthermore, ashas ra phenolic condensation product, the tem- Be it known that I, LOUIS T.FREDERICK,

already been pointed out, my process .re-

quires less complicated apparatus and less sation product, it is to beunderstood that any equivalent materials may be substituted for them, asconvenience or necessity may require. It is also to be understood thatthe steps of my process may be variously modified by persons skilled inthe art, and that my invention is therefore limited only by the. scopeof theappended claims.

I claim as my invention:

1. A process of making tubes that comprises treating fibrous materialwith an adhesive material comprising a phenolic con-- densation product,winding the treated fibrous material upon a mandrel without heat orpressure, subjecting the wound material to heat and lo molding pressureagainst its entire outer surface while upon the said mandrel, andwithdrawing the said mandrel.

2. The process of making tubes that comprises impregnating a sheet offibrous material wilh a phenolic condensation product as a binder,winding a dry sheet so treatedabont a mandrel without applying heat andpressure to build up a tubular body upon the A mamlrel. and firstsoftening and then hardening the binder by applying heat and pressureagainst the entire outer surface ofthe tubular body so formed.

In testimony whereof I have hereunto subseribed my name this 11th day ofDec., 1914.

Louis '1. FREDERICK.

Witnesses:

Gonom-E. McGEu, B. B. Hmns.

70 skill .on the part of the operatives than the a

